"Seth Rogan (sic) sorry I didnt bow down when I asked 2 meet u was probably a bit shy and didn't want to be over the top but still. love ur movies," the 20-year-old singer tweeted on Thursday.

Earlier this week, Rogen, who has publicly bashed Bieber in the past, told Stern, "I've met him a few times. He's a good example of someone who you meet who you think you are going to hate and then you get to hate him as much as you [thought]...You meet him and he lives up to every one of your expectations of how you hope he'll be."

Rogen said he first met Bieber backstage at a German talk show after Bieber requested a meeting with him. When they were introduced, Rogen says the Biebs was acting too cool for school.

Rogen recalled thinking, "What the f--k, I don't want to meet you! Don't act all nonplussed to meet me. I didn't want to meet you. I was totally cool with not meeting you"

He added, "I was like, ‘He's a little bit of a mother--ker. Whatever. He's a bit of a d--k."

But that wasn't there only ill-fated encounter. "I saw him again at like an MTV awards show, he literally had a snake wrapped around his f--king wrist that he was wearing," Rogen said. "Like a live snake as an accoutrement. I was like, ‘What the f--k?' I talked to him for like five minutes. I just remember thinking, ‘F--k this kid'...I remember thinking, 'He's a piece of s--t.'"

Meanwhile, on Wednesday's Today, where he was promoting his new comedy, Neighbors, Rogen humorously defended his comments on Bieber.

"To me, the idea that, like, a grown man doesn't like Justin Bieber is not a controversial thought," the 32-year-old actor said to cohost Matt Lauer. "Why would I (like him)? It would be much weirder if I did like Justin Bieber."